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40 Cards in this Set
- Front
- Back
point mutations
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permanent, sudden qualitative alterations that arise as a result of addition, deletion, or substitution of one or more bases in region of gene
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spontaneous mutations
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mutations that result from chemical and physical components in organism's environment
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induced mutations
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genetic changes resulting from organism's exposure to artificial physical or chemical mutagen
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conjugation
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mating process between "sexually" differentiated bacterial strains that allow unidirectional transfer of genetic material
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transduction
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a bacteriophage-mediated transfer of genetic material from one cell to another
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transformation
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a genetic alteration in a cell resulting from the introduction of free DNA from the environment across the cell membrane
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Ames test
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a bacterial test system for chemical carcinogenicity
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carcinogenicity
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linked to mutagenicity
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Salmonella typhimurium
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organism used in Ames test with HIS- and BIO-
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bacteriophage
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virus that attacks bacteria
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bacteriophage attachment
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adsorbs into bacterial cell surface by means of tail fibers and base plates. injects nucleic acid into the bacterium during penetration (tail sheath contracts, driving the tail core through cell wall)
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plaque formation
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new phages are released from original infected cell to infect other cells which are lysed - produces a clearing or plaque
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salt solution
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neutralizes the negative charge of the DNA's phosphate units
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detergent (Dawn)
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helps to remove cellular membrane and allows access to DNA (emulsifies or breaks up the fats in the cell membrane)
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meat tenderizer
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destroys enzymes which could digest the DNA; heat enhances this action
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ethanol
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separation of layers- DNA (white stringy matter) rises into the alcohol layer while protein and cellular debris is in the bottom
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biofilms
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composed of populations or communities of microorganisms adhering to environmental surfaces
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microbial mats
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specialized microbial communities composed mainly of photosynthetic prokaryotes
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benefits of biofilms
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break down organic wastes:
water treatment septic systems |
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disadvantages of biofilms
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dental carries
contamination of artificial surfaces used to treat patients resistant to antibiotics |
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biofilm formation steps
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1. reversible adsorption of bacteria (forms sticky layer)
2. irreversible attachment of bacteria (becomes planted) 3. growth and division of bacteria 4. exopolymer production and biofilm formation 5. attachment of other organisms to biofilm |
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operon
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a unit made up of linked genes that is thought to regulate other genes responsible for protein synthesis. consists of a promoter, an operator, and the structural genes they control
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promoter
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the region where RNA polymerase binds
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operator
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signals whether transcription will occur
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nar operon
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encodes E. coli genes for nitrate reductase
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ara operon
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encodes E. coli genes for catabolism of arabinose
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bioinformatics
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branch of science devoted to computational information management systems used to collect, store, analyze, and disseminate biological information - identification and classification of bacteria
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16s rRNA DNA segment
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easily compared because found in all organisms with the same function
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rRNA gene sequencing advantages
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1. all cells contain ribosomes and rRNA
2. greater relation equates to fewer differences in sequences 3. RNA genes are highly conserved 4. does not require cell to be cultured |
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signature sequences
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5-10 base pair sequence always found in a particular group of organisms - specific location in sequence
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biosafety levels: level 1
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organisms not known to cause human disease; minimal hazard
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biosafety levels: level 2
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agents of moderate potential hazard
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biosafety levels: level 3
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clinical, diagnostic, teaching, research with indigenous agents; serious hazard - like leprosy
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biosafety levels: level 4
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exotic organisms; life threatening disease potential & no vaccines - like Ebola
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PCR (polymerase chain reaction)
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tool for amplifying a single nucleic acid sequence of DNA or RNA until there is enough material to detect and identify the source
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steps of PCR
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1. heat denaturation
2. annealing of primer pair 3. primer extension |
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differential medium
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a medium that distinguishes between multiple bacteria by appearance of colonies grown on a plate. for example, colonies of various bacteria may be colored differently.
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selective medium
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a medium that suppresses growth of one type of bacteria, but permits the growth of other kinds of bacteria
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chemically defined media
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made from known amounts of pure chemical compounds
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artificial/complex media
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commonly used and works for most bacteria. exact chemical composition is not known.
ex: nutrient broth, yeast extract broth |